feat(sdk-coin-flr): add Export C to P chain support

[nayandas190]

Ticket: WIN-7886

• Add atomic transaction builder integration for cross-chain operations
• Add explainTransaction support for Export transactions
• Add validateHopPrebuild for Export type hop transactions
• Add verifySignatureForAtomicTransaction for signature verification
• Add createHopTransactionParams with Export type support
• Add unit tests for Export transaction explanation

[Copilot]

Pull request overview

This PR adds support for Export C to P chain atomic transactions in the Flare (FLR) SDK coin module, enabling cross-chain operations between Flare's C-chain (EVM-compatible) and P-chain. The implementation closely follows the established patterns from the AVAX C-chain implementation.

Key Changes:

• Integrated atomic transaction builder (FlrPLib) for cross-chain Export transactions
• Added transaction explanation, verification, and signature validation for atomic transactions
• Implemented hop transaction parameter creation with Export type support

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
modules/sdk-coin-flr/src/flr.ts	Main implementation adding atomic transaction support including explainTransaction, verifyTransaction, validateHopPrebuild, createHopTransactionParams, and helper methods for Export C to P transactions
modules/sdk-coin-flr/src/iface.ts	New interface definitions exported publicly including ExplainTransactionOptions, HopParams, HopPrebuild, and extended BuildOptions/TransactionPrebuild types
modules/sdk-coin-flr/src/index.ts	Exports new iface module for public API access
modules/sdk-coin-flr/test/unit/flr.ts	Unit tests for P-chain address validation, hop transaction parameters, transaction explanation, and basic transaction verification
modules/sdk-coin-flr/test/resources.ts	Test data for Export C to P transactions including addresses, transaction hex values, and metadata
modules/sdk-coin-flr/package.json	Added dependencies for atomic transactions (sdk-coin-flrp, secp256k1, keccak, ethereumjs-util, bignumber.js)

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[nayandas190]

I have addressed all the above review comments.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

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